Grid support structure



Nov. 23, 1948.

L. B.,CUR-T|$ GRID SUPPORT STRUCTURE Filed April 30, 946

Patented Nov. 23, 1948 GRIDHSUPPORT STRUCTURE Lucien B. Curtis, Verona, N; J., assignorto Radio .Gorporation'of America, a: corporation of Dela- .ware

Application April30, 1946', Serial No. 665,954

The present invention relates to electron discharge tubes for superheterodyne reception which, more specifically, utilizes converter type tubes having multiple grids.

The need for portable radio and electronic equipment and the demands of high frequency reception create the outstanding problem of reducing the size of the tube structure. .In the solution of this problem, however, the decrease in the size of the electron discharge tubes is physically limited in one respect by the need for necessary spacing of the. electrodes within the envelope to provide sufficient insulation between the several electrode structures. Also, there is a further limitation due to: the increase of cost of manufacture relative to the decrease of the size of tube structure.

One solution of the problem has been to utilize the envelope of a metal tube as the plate electrode. However, this. has introduced new problems of insulation and cooling.

An object of this invention is the arrangement of the tube structure in a novel manner so as to reduce the diameter size of the tube.

A more particular object of the invention is to provide a common support for two equipotential grids without destroying the utility of the space between the grids.

.9G1aims. (Cl. 25027.5)

My tube construction helps: to solve the problem of reducing the size of tube structure in providing a more compact arrangement of the electrode elements by eliminating one set of supporting side rod members within the envelope and utilizing another set of side rod members as a common support for two separate but, equipotential grids. This arrangement is so devised as to provide an unobstructed space between the two grids for the mounting of a third grid.

The novel features which I believe to be characteristic of my invention. are set forth with particularity in the appended claims, but the invention itself. will best be understood by reference to the following description taken in connection with the accompanying drawing, in which- Fig. 1 is a cross-section transverse to the longitudinal axis of a conventional tube of the converter type;

Fig. 2 is a view in perspective, with parts removed, of an electron discharge tube embodying my invention;

Fig. 3 is a cross-section of the tube of Fig. 2 along line 3-3 according to my invention; and

Fig. 4 shows a detailed form of a grid structure according to my invention.

In Fig. 1 is disclosed a conventional tube of the converter type having a cathode K. A series of concentric grids G1 through G5 are disclosed surrounding the cathode K. A. cylindrical plate P is also mounted concentric with the cathode and enclosing the series of grids. All these structures are enclosed within the envelope E of the tube. In this tube in Figure 1, grids G2 and G4 are screen grids of the same potential and are connected together Within the tube as is well-known in the art.

Figs. 2 and 3 disclose in detail my invention. The tube, disclosed in these figures, has an envelope 2. Insulating spacers 3 at the top and bottom of the tube hold in alignment the cathode 4 and the electrode supporting side rods 1, 9 and I3. Spaced outwardly. from the cathode and in concentric arrangement (Fig. 3) are the control grid 6, screen grids-8 and I2, signal grid I0, suppressor grid [4, and plate I6. Control grid 6 is supported by side rods 1. Screen grids 8 and I2 corresponding to grids G2 and G4 of Fig. 1, are mounted on common side rods 9. This arrangement is possible as these screen grids 8 and i2 operate at the same. potential. In the preferred form of my invention. the inner grid 8 is formed asan elliptical right section of a cylinder, while screen, grid 12. is of a circular cylindrical shape. These two grids are brought close together at two points along the transverse axis of the elliptical grid 8, in such amanner as to be supported by the common supporting rods 9. This arrangement leaves enclosed and unobstructed spaces 5 between the outer surface of the screen grid 8 and the inner surface of the screen grid [2. These enclosed spaces are utilized in mounting a foraminous electrode such as a signal electrode l0 upon side rods H. To conform with this, arrangement, the signal electrode in is preferably made of, two part-s, one of which is shown in detail in Fig; 4, each part being supported by one rod ll'. This preferred form of the grid may comprise a mesh reinforced. at the top and bottom by metal straps IS. The two parts of grid H) are of cylindrical form and one is mounted in each of the unobstructed spaces -5 between grids 8 and [2. Furthermore, the parts of grid ID are preferably concentric with the cathode 4.

It is obvious that other types of control electrodes, well known in the art, may be substituted for the particular structure of Fig. 4. If it is desired to provide a larger space 5, the grid 12 can also be formed with an elliptical section which has its transverse axis perpendicular to the plane of the common support rods 9. Grids 8 and I2 may be either mesh or wound as is well known in the art.

Thus, the equipotential grids of a converter tube, are arranged in a much smaller space and equipotential grids upon common side rods, one,

pair of supporting side rods of the conventional type tube is eliminated.

While certain specific embodiments have been illustrated and described, it will be understood that various changes and modifications may be made therein without departing from the spirit and scope of the invention.

What I claim specifically is:

An electron discharge device comprising a first grid and a second grid, a support rod supporting both said first grid and said second grid, said second grid completely enclosing said first grid and forming with said first grid an unobstructed space therebetween, and a control electrode mounted within said space. v

2. An electron discharge device comprising a first screen grid and a second screen grid, a plurality of support rods each supporting both said first screen grid and said second screen grid, said second screen grid completely enclosing said first screen grid and forming with said first screen girid an unobstructed space therebetween, and a control electrode mounted within said space.

3. An electron discharge device comprising a plurality of support rods, a first screen grid mounted on said support rods, a second screen grid also mounted on said support rods, said second screen grid completelyenclosing said first screen grid and having portions thereof spaced from said first screen grid, and a control electrode mounted within the space between said first screen grid and said second screengrid.

4, An electron discharge device including a cathode for emitting electrons, a first cylindrical screen grid having an elliptical right section concentric with said cathode, a'second circular cylindrical screen grid concentrically surrounding said first screen'grid and forming an enclosed space on either side of said first elliptical screen grid, a plurality of side rods each provid ing a common support for said screen grids along their cylindrical surfaces, a control grid comprising tw-o cylindrical portions, said portions being mounted concentrically with said cylindrical grids, and one of said portions being within each enclosed space. 1

5. An electron discharge device comprising an envelope, a first and second screen electrode mounted within said envelope, said firstscreen electrode being concentric with and enclosing said second screen electrode, said first and second screen electrodes each adjoining the other at respectively two portions thereof, a pair of common side rods, each of said side rods supporting both said first screen electrode and the said second screen electrode at one of the adjoining portions,

4 said first and second screen electrodes forming two enclosed spaces therebetween, a third control electrode having two portions thereof, one of said two portions mounted within each of said enclosed spaces.

6. An electron discharge device including a first screen grid, a second screen grid completely enclosing said first screen grid, means common to said first and second grids supporting said grids, said grids providing an enclosed space therebetween, a third control electrode within said enclosed space, means rigidly supporting said third electrode within said enclosed space.

7; An electron discharge device comprising a first cylindrical screen grid, a second cylindrical screen grid completely enclosing and concentric with said first screen grid, side rod means common to said first and second grids supporting said grids, 'said grids providing two enclosed spaces therebetween, a third grid electrode including two portions, one of said portions being within each of said enclosed spaces, means rigidly supporting said third grid portions respectively within said enclosed spaces.

8. An electron discharge device including a first cylindrical screen grid having an elliptical right section, a second circular cylindrical screen grid concentrically surrounding said first screen grid, a pair of spaced side rods positioned along the transverse axis of said first elliptical grid, said first and second screen grids being rigidly mounted on said pair ofside rods whereby two enclosed spaces are formed between said first and second grids, a control grid comprising two portions, a second pair of side rods, one of said second side rods supporting one of said portions concentrically with said cylindrical grids within each of said enclosed spaces.

9. Anelectron discharge device including a cathode for supplying electrons, an anode spaced from said cathode for receiving said electrons, a first control electrode surrounding said cathode, a first and second foraminous screen electrode enclosing said first electrode and said cathode, said electrodes mounted between said cathode and saidanode, oneof said screen electrodes having two spaced portions thereof adjoining 'to the other screen electrode, a'pairof common side rods,'each of said side rods supporting both said first and second screen electrodes at one of said adjoining portions whereby two enclosed spaces are formed betweensaid first and second screen electrodes, a second control electrode comprising two portions thereof, one of said portions being rigidly mounted between said first and second screen electrodes and within each of said enclosed spaces.

LUCIEN B. CURTIS.

, REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 2,146,016 Herold Feb. 7, 1939 

